1. Field of the Invention
This invention relates to a windshield wiper system and, more particularly, to a windshield wiper system which utilizes at least one flexible member which bends or flexes to compensate for compression loads in excess of a predetermined load.
2. Description of the Related Art
In the field of windshield wiper systems, wiper arms having wiper blades thereon are driven from a park position, where the blades are often situated at either the bottom of or below a windshield of a vehicle, through an inwipe position, to an outwipe position. During normal wiping operations, the blades oscillate between the inwipe and outwipe positions to clean the windshield of debris or particles, such as ice, snow or other debris. It is not uncommon that snow or ice can accumulate on the windshield and prevent the wiper blades from, for example, fully retracting from the inwipe position to the park position when a user actuates a wiper switch to an off position.
When the debris blocks the wiper arms and blades, a considerable amount of stress is imparted on the wiper linkage and drive motor which drives the blades. For example, a motor drive link, which couples the drive shaft of the motor to the drive linkage which drives the wiper arms, often experiences a compressive force. The linkage members of the wiper systems have in the past been stiffened to reduce expansion and shrinkage in order to avoid changing the wipe pattern requirements for the vehicles. However, in freezing, snowy weather, the snow and ice packs at the bottom of the windshield causes a restriction in the movement in the wiper arm and blade. Because of the rigidity of the motor drive link, the housing which houses the drive gears of the drive motor may crack or break. It has also been experienced that one or more drive plates which directly or indirectly couple the drive link to other linkage have been known to fracture or crack.
Accordingly, what is needed is a simple, yet effective, linkage system which utilizes one or more linkage arms having a relatively low modulus of elasticity with relatively high elongation and fatigue properties to facilitate avoiding the problems of the past.
It is, therefore, a primary object of the invention to provide a system and method for driving a windshield wiper blade such that it can accommodate relatively high loads resulting from undesired fatigue conditions.
It is another object of the invention to provide a wiper blade linkage system which utilizes at least one flexible arm which is capable of flexing when a compressive load exceeds a predetermined amount, such as 30 percent higher than a maximum working load.
It is another object of the invention to provide a system and method which can accommodate for compressive loads on linkage components resulting from fatigue conditions, such as snow or ice situated on a windshield.
In one aspect, this invention comprises a windshield wiper drive linkage for use in a wiper system comprising a plurality of linkage arms, at least one of the plurality of linkage arms comprising a flexible arm which bends to facilitate preventing damage to components in the wiper system when a compressive load applied to at least one of the plurality of linkage arms exceeds a predetermined load as a result of a fatigue condition.
In another aspect, this invention comprises a wiper system comprising a first wiper, a second wiper, a windshield wiper drive linkage coupled to the first and second wipers, a drive motor coupled to the windshield wiper drive linkage and the windshield wiper drive linkage comprising a plurality of linkage arms coupled to the first and second wipers and the drive motor, at least one of the linkage arms comprising a flexible arm which bends to facilitate preventing damage to components in the wiper system when a compressive load applied to one linkage arms exceeds a predetermined load as a result of a fatigue condition.
In yet another aspect, this invention comprises a method of driving at least one wiper blade in a windshield wiper system comprising the steps of providing a drive motor for driving the at least one wiper blade, providing linkage for linking at least one wiper blade to the drive motor, the linkage comprising a flexible arm which bends to facilitate preventing damage to components in the wiper system when a compressive load applied to at least one linkage arms exceeds a predetermined load as a result of a fatigue condition.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.